Uptake and translocation of phosphorus in eelgrass (Zostera marina)

Light-dependent uptake, translocation and foliar release of phosphorus by the intertidal seagrass Zostera noltii Hornem.

“…This fact is in agreement with the results of several studies carried out in Z. marina (McRoy & Barsdate, 1970;Brix & Lyngby, 1985), indicating that the uptake and posterior translocation are coupled to the metabolic activity of the plants (McRoy & Barsdate, 1970). The amount of P translocated by Z. noltii constituted a maximum of ~70% in the light and 33% in the dark of the total amount of P taken up after an incubation time of 99 h. McRoy & Barsdate (1970) reported that 50% (in the light) and 13% (in the dark) of the total amount ofP taken up by Z. marina, was translocated to the leaves after an incubation time of 50 h. However, lower amounts were reported by Penh ale & Thayer (1980) and Brix & Lyngby (1985) in the same species. The former authors found that 1.1-21.4% of the P absorbed in light by the underground parts was translocated to the leaves in 12 h incubation.…”

“…In reality, the specific activity changes when the isotope taken up is diluted with the unlabeled material in the plant. Similar assumptions have been made in other studies (McRoy & Barsdate, 1970;McRoy & Goering, 1974;Wetzel & Penhale, 1979;Penhale & Thayer, 1980;Brix & Lyngby, 1985).…”

“…The former authors found that 1.1-21.4% of the P absorbed in light by the underground parts was translocated to the leaves in 12 h incubation. Brix & Lyngby (1985) reported a foliar translocation of 4 % of the nutrient taken up by roots and rhizomes in an incubation time of 120 h. In our study, the translocated P was mainly accumulated in the youngest leaf (N o. 1), which is the most actively growing part, acting as a natural sink for P and N (Welsh & Denny, 1979;Iizumi & Hattori, 1982;Brix & Lyngby, 1985;Perez-Llorens & Niell, 1989;PerezLlorens et aI., 1991).…”

“…Several later experiments carried out in Z. marina as well as in other aquatic macrophytes showed very low or zero P release to the water from healthy leaves (Bole & Alan, 1978;Kirkman et al, 1979;Welsh & Denny, 1979;Barko & Smart, 1980;Penh ale & Thayer, 1980;Carignan & Kalff, 1982;Gabrielson et al, 1984;Thursby & Harlin, 1984;Brix & Lyngby, 1985;Moeller et al, 1988). Thus, the literature provides conflicting data on foliar release by actively growing macrophytes.…”

Modelling growth of Ruppia cirrhosa

“…(2), gross production is a function of P max and I k . It was assumed that R. cirrhosa is not nutrient limited, since rooted aquatic macrophytes usually uptake nutrients both from the bottom and from the water column (Short and McRoy, 1984;Thursby and Harlin, 1984;Harlin, 1995), transferring them through different parts of the plant (Brix and Lyngby, 1985). Thus, P max may be assumed to depend mainly on temperature and physiologic adaptation, (Menendez and Peñuelas, 1993) as has been observed in algae (Davison, 1991;Falkowski and LaRoche, 1991).…”